Water heater



Sept 10, 1957 E. H. HAUGEN 2,805,648

WATER HEATER 1N VENTOR EDMoN D H.- HAUGEN ATTORNEYS.

5 Sheets-Sheet 2 E. H. HAUGEN WATER HEATER Sept. l0, 1957 Filed Aug. 51.195o INVENTOR, EDMrjxo' H. HAUGEN BY Y ATTQRNEYS Sept. l0, 1957 E. H.`HAUGEN 2,805,648

y WATER HEATER l Filed Aug. 31. 1950 5 Sheets-Sheet 3 INVENTOR EDMoND H.HAUGEN n @JJM ATTORNEYS Sept. 10, 1957 V E. H. HAUGEN 2,805,648

WATER HEATER y Filed Aug. 3l, 1950 5 Sheets-Sheet 4 /5 I l I I Fi ..5 II i I l i /2 s l I .9 s .-.2/ a II 7 l g I i I I g I 4/ I l I@ lINVENTOR EDMNo H. HAUGEN ATTORNEYS Sept. 10, 1957 E. H. HAUGEN WATERHEATER 5 Sheets-Sheet 5 Filed Aug. 31, 1950 INVENTOR .EoMoNu H. HAUGEN.

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v ATTORNEYS nited States arent WATER HEATER Edmond H. Haugen,Birmingham, Mich., assignor, by mesne assignments, to Scaife Company,Uakrnont, Pa., a corporation of Pennsylvania Application August 31,1950, Serial No. 182,565

7 Claims. (Cl. 122=33) This application relates to heater apparatus andparticularly to such wherein domestic hot water and hot water for theradiators or other space heating devices are heated by acommon burner.

Since the recent war there has been considerable expansion in housing,particularly in the eld of small houses, more of which are being builtbecause of the increased costs of building. Many of these small houseshave no basements and must install the entire heating unit in either thekitchen or a utility room on the first floor. The -heater apparatus ofthe present invention is particularly adaptable for small houses, andessentially it comprises a special fabricated boiler within which ismounted a Wall llame oil burner, the boiler being surrounded by aninsulating cabinet so that it is a fire proof insulated unit that doesnot radiate much heat into the surrounding room, and specialarrangements are provided for heating the domestic hot water. Preferablythe domestic hot water coil is suspended within the water space of theboiler. Details of these and other novel assemblies and sub-assemblieswill appear as the description proceeds.

It is a major object of my invention to provide a novel heater apparatuswherein the coil assembly for instantaneously heating domestic hot Wateris suspended within the water space of the boiler in such a manner as tobe out of Contact with the walls of the boiler and at the same time notto interfere unduly with circulation of the boiler water.

A further object of the invention is to provide a novel boilerconstruction for a hot water heater wherein certain of the walls areeccentric or otherwise relatively more widely spaced than others toprovide room for a coil for circulating domestic water to be heatedthrough the hot water boiler space without unduly interfering withcirculation of boiler Water.

It is a further object of the invention to provide a novel combinationof a boiler and domestic hot water heater wherein the coil for thedomestic hot water is mounted as a unit upon a plate or other closuremember secured to the top wall of the boiler whereby the coil issuspended freely in the boiler water.

lt is a further object ofthe invention to provide a novel domestic watercoil arrangement and mounting for a hot water heater.

A further object of the invention is to prvide a novel automatic draftstabilizer assembly wherein air from a point adjacent the bottom of theheater is drawn upwardly through a passage and combined with theoutgoing combustion products. Y

Further objects of the invention will presently appear as thedescription proceeds in connection with the appended claims and theannexed drawings wherein:

Figure l is a top plan view of a hot water heater according to apreferred embodiment of the invention, par tially broken away to showcertain details and particularly showing the arrangement of the boiler,the domestic water together with water tight joints to heater coillmounting, the pump and distribution piping, and the expansion tank;

Figure 2 is a front elevation of the water heater of Figure l, brokenaway to illustrate the suspension mounting of the coil assembly forheating domestic hot water;

Figure 3 is a side elevation of the water heater of Figures l and 2,illustrating the water distribution arrangements and partially brokenaway to show the pump mounting and the draft stabilizer;

Figure 4 is a top plan view of a unitary welded sheet metal boilerhaving eccentric inner and outer walls which is used in the preferredembodiment of myinvention;

Figure 5 is a side elevation mainly in section through the boiler ofFigure 4;

Figure 6 is a rear elevation of the draft stabilizer unit apart from itsassembly with the rest of the water heater illustrating particularly thedeector where the draft air joins the combustion gases before passinginto the llue; and

Figure 7 is a photographic view of a domestic water heating coil andmounting plate wherein only a single coil is used and which may besubstituted for the dual coil unit illustrated in Figures 1 and 2.

The novel water heater apparatus of my invention cornprises a cabinet 11surrounding a boiler 12 which has mounted in it a domestic hot waterheating coil assembly indicated at 13. Boiler 12 is connected to anexpansion tank 14, as by a suitable pipe 15. A burner unit, which ispreferably a wall flame oil burner 16, is mounted on a hearth at thebottom of the boiler, and after traversing the combustion chamber withinthe boiler the products of combustion escape through a flue assembly.

Boiler 12 is best illustrated in Figures 4 and 5 wherein the boilerwalls are all made of sheet steel sections having a gage of aboutone-fourth of an inch permanently welded provide a novel vunitary Waterbacked combustion chamber.

The boiler assembly comprises an outer cylindrical member 17 thatdefines the outer wall of the water space 18 within the boiler. Thelower part of the combustion chamber within the boiler or what is knownas the primary combustion chamber 19 is surrounded by a cylindricalmember 21 displaced rearwardly from the front of the unit so as toappear in plan (Figure 4) as eccentric with respect to outer wall member17. Member 21 defines the lower inner wall of the boiler Water space. l

The upper or secondary combustion chamber 22 is surrounded by a wallmember 23 which is mairdy cylindrical and concentric with thelowercombustion chamber wall 21 but is formed with rearwardly projectingwalls 24 and 25 to provide a ilue connecting throat as indicated inFigure 4. The bottom of lower combustion chamber 19 is open as indicatedat 26 to receive the burner and flame rim as will appear. The bottom ofthe water space between walls 17 and 21 is closed by a suitably shapedannular steel member 27 which'is known as a mud ring and Yis welded atits inner and outer peripheries to walls 17 and 21, thereby sealing offthe entire bottom of the vboiler assembly. The top of lower combustionchamber 19 is defined by a circular steel plate 28 welded about itsperiphery to member 21 and it has a circular opening 29 concentric withmember 21. The bottom of secondary combustion chamber 22 is closed by agenerally circular welded plate 31 concentric with member 23Ywhich, atthe flue outlet side, is provided with an extension 32 that extends intoContact with the inner surface of the outer boiler wall 17. A centralaperture 33 is formed in plate 31.

Walls 28 and 31 are parallel and horizontal and are spaced apart asillustrated. A series of small spacer blocks 34 are welded between themin the water space to aid in maintaining them apart. In addition `walls28 and 31 are connected by a cylindrical collar 35 which is weldedwithin -openings 29 and 33, and projects up into the upper combustionchamber as illustrated in Figure 5. The boiler top wall is a generallyC-shaped steel. plate 36 that` extends from `wall 24 to wall 2S, beingwelded to the tops of these walls and member 23 so as to complete thetop closure of the boiler water space.

I have thus provided an all steel welded plate boiler unit wherein theentire water space is sealed by welded joints. Lower wall `21 provides acontinuous smooth water backed surface in the primary combustionchamber. The products of combusiton successively traverse t primarycombustion chamber 19, throat 35, upper combustion chamber 22 andtheoutlet above extension32 between walls 24 `and 25. The eccentricarrangement of the inner and outerboiler walls provides a largeforwardwater space 37 wherein the coil assembly for the domestic hot watersupply may be disposed as will appear. It is obvious that space 37 neednot be dened by eccentric circular walls, although that structure hasbeen found extremely adaptable to speed of assembly and eiicient boileroperation, but may `be defined by other wall arrangements.

While I have here described my boiler as made up of circular walledsections, it will be understood that the overall scope of the inventionis not so limited. One limit on the size of circular boilers is themaximum diameter than can pass through the usual building doorway. Theboiler therefore may be oval or generally rectangular in shape, sincesheet steel may be readily worked to obtain the optimum shape. It hasbeen found that generally rectangular and oval boilers can be increasedin length while maintaining the maximum permissible width, therebyproviding a higher output.

Within the boiler unit, supportstrips 38 and 39 welded to walls 23 and17 respectively help to support upper wall 36 from below. Above bottomwall 27 a series of spaced projections 41 are welded to the boiler wallsfor locating wall 27 in the assembly. A plurality of lugs 42 are weldedto depend from mud ring 27 below the level ofthe surrounding walls 21and 17 for mounting the boiler on the rest of the hearth assembly.

Figures 1-3 illustrate the water distribution system for pumping the hotwater from the boiler to the radiators or other space heating devices ofthe house and return. It essentially comprises a pump 43 driven by anelectric motor 44. The pump and motor assembly may be mounted on abracket 45 connected to the frame of the surrounding cabinet. vention,however, the pump assembly and connected piping provide a selfsupporting rigid assembly needing'no added support from the cabinet. Theoutlet side of the pump is connected by means of a coupling or T tting46 with a pipe 47 whichleads downand thence to the t.

space heaters. A `valve 48 is provided in this line. A pipe 49 isconnected to another outlet in coupling 46 and to a fitting 51 threadedinto a iiange 52 in wall 17 of the boiler. Fitting 51 is located at thetop of the boiler water space so that any Water pumped up through pipe49 will return directly into thte top of the boiler. A valve 53is'provided in line 49.` Valves 48 and 53 are adjustable to control therate of flow of water therethrough but either may be shut off completelyas will appear.

The inlet side of pump 43 s connectedby a pipe S4 with a coupling or Tfitting 55 having one inlet connected to the return line S6 from thespace heaters (not shown). The other inlet ofcoupling S is connected bya pipe 57V to a fitting 58 threaded into a flanged outlet 59 in thelower part of boiler wall 17. The inlet and outlet sides of pump 43 areconnected to pipes 49 and 54 respectively through` adapter flangeassemblies 61 and 62 respectively which enable the pump to be readilyremoved for repair or replacement.

In most `embodiments of the int During operation of the pump, hot waterfrom the lower part of the boiler is drawn off through pipe 57, coupling55 and pipe 54 and pumped out through coupling 46. If valve 48 isclosed, as it may be during the summer when space heating is notnecessary and the action of convection currents within the boiler waterspace is not adequate to suitably heat the domestic hot water and withvalve 53 open, all of the hot water will be pumped through pipe 49 intothe top of the boiler, thus providing a forced recirculation of theboiler water that speedily results in heating of all the boiler waterfor quickly indirectly heating the suspended domestic water coil.

When, as in the winter, it is desired to circulate hot water through theradiators as when heat is demanded in the house, both valves 48 and 53are open and the ow through coupling 46 split as indicated in Figure 3.The valves 48 and 53 are suitably adjusted to provide the desired rateof flow of water in each circuit. Under these conditions the hot waterbeing pumped out of the boiler where it is lowest in temperature isadmixed with some of the cooler return water before it is pumped up- Ywardly to pass partly out through and, into the system c water.

and partly back into the top of the boiler. In this manner I am enabledto raise the average boiler water tempera ture and maintain a moreuniform heating temperature for the Water in the space heating systemthroughout the house and to maintain the temperature of the domestic hotwater at a higher level. If for some reason it is desired to maintaincirculation through the radiators while the coil for the domestic watertank is being repaired, or if the coil is omitted and a substitute orseparate source of domestic hot water is used, valve 53 in the upperpipe may be closed.

The verticaltexpansion tank 14 is shown in Figures l, 2 and 3. This tankis rigidly supported on the framework within one corner of the cabinetpreferably with its bottom spaced above the oor of the cabinet. Abovetank 14 is a coupling 63 from which depends a pipe 64 that extendsthrough a top flanged opening in the tank down nearly to the bottomwithin the tank, so that any Water which enters the tank will bedeposited near its bottom. Expansion tank 14 is connected to the boilerthrough coupling 63 and pipe 1S, the latter being shown in Figure l asextending over the top of the boiler to a union 65 that is threaded intoan aperture in the plate 66 that supports the domestic water heatingcoil. In this manner, any excess water in the space heating system thatarises out of expansion of the heated boiler water will overflow throughpipe 15 into the expansion tank. A safety valve 60 for the system isalso connected to coupling 63 asillustrated in Figure l. By thusproviding such a vertical expansion tank in the assembly, I supply thesystem with a greater capacity expansion tank having a larger aircushion therewithin.

An extremely important 'feature of my invention is the fact that ythecoil assembly 13 for heating the domestic hot water is readily removablymounted in the heater. Top wall 36 of the boiler is formed with anarcuate elongated, generally kidney-shaped opening 67 that is closed bysimilarly shaped plate 66 attached to the top wall of the boiler unit asby a plurality of studs 68. Plate 66 in eiect forms a part of the topboiler wall and the coil 13 itself is entirely suspended from it in theboiler Normally plate 66 is tightly fastened upon the top wall of theboiler with suitable gaskets between them.

Referring to Figure 2, the domestic hot water heating coil assemblycomprises two separate coils of copper `tubing 71 and 72. Plate 66 isformed with suitable openings through which project threaded nipplesupstanding from fittings 73, 74, 75 and 76. Nuts 77-80 on the respectivenipples clamp these fittings tightly to the underside of the plate 66.4Coil 71 comprises a continuous tube having an end portion 81 connectedto fitting 73, three vertically spaced cylindrically coiled horizontalsections 82, 83 and 84 in series, and a riser 85 connected to fitting74. Coil 72 comprises a continuous tube having an end portion 86connected to fitting 76, three Vertically spaced cylindrically coiledhorizontal sections 87, 88 and 89 in series and a riser 91 connected tofitting 75.

Coils 71 and 72 are connected in series by a jumper tube 92 connectingthe nipples of fittings 74 and 75 above plate 66. The fitting 73 isconnected to the cool water inlet pipe 93, and fitting 76 is connectedto pipe 94 that goes to the domestic hot water tap (not shown). As hotwater is drawn from the coil, it will be automatically refilled withcool water entering from pipe 93 under normal line pressure to beinstantly heated by the boiler water as will appear.

Each of coils 71 and 72 is made of thin-walled copper tubing having anouter diameter of 3% inch to 1-/2 inch, and the coils are substantiallyrigid self sustaining units extending down into the boiler water. Thearrangement provides a large area for heat exchange, preferably at leastten square feet or more for the entire coil assembly 13. As illustratedin Figure 1, coil assembly 13 forms a generally arcuate or kidney-shapedunit that follows the circumferential contour of space 37 withouttouching any of the boiler side walls.

The rotary wall flame oil burner unit 16 may be of the type illustratedin Powers et al. Patent 2,491,517 or the United States Letters Patent ofEdmond H. Haugen No. 2,616,402, issued November 4, 1952, and it projectsupwardly through a suitable opening in a hearth assembly rigidly securedacross the bottom of primary combustion chamber 19. The hearth assemblycomprises a steel plate 95 secured as by bolts 96 to a boiler basestructure 97 that supports the entire heater assembly on the floor. Theburner unit 16 is secured to plate 95 as by the bolts 98. A cylindricalsteel shell 99 upstanding from plate 95 surrounds a layer 101 of fireresistant cement or other refractory material which serves as the hearthsurface, and an annular flame rim 102 is welded above the innerperiphery of shell 99 to a series of spaced upright brackets 99' whichserve as attachment members for securing shell 99 and ame rim 102 to theplate 95. See Figure 2. A series of grilles 103 are mounted on the flamerim in accord with usual practice.

The plate 95, shell 99, cement hearth 101 and the flame rim 102 arepreferably factory assembled, and in installation in the field thehearth is completed by filling refractory cement into the space betweenshell 99 and wall 21 as illustrated in Figure 2.

Above the hearth, oil droplets from the rotating inger tubes 104 areatomized at the flame rim 102 and admixed with air pumped outwardly byfan 105. An igniter 100 is provided adjacent the flame rim. This burnerassembly provides an even annular iiame around the lower periphery ofwall 21 which is free of openings and pro- I jections and is heateduniformly by the hot products of combustion that pass upwardly over itand through throat 35 into the secondary combustion chamber 22. Insteadof the hearth assembly above described, a steel hearth and shield ringassembly such as disclosed in Haugen Patent No. 2,616,402, issuedNovember 4, 1952 may be used.

The top of the secondary combustion chamber is closed by a suitablecover assembly 110 as illustrated in Figure 3. A tubular baffle 106having a top plate 106a and an opening 107 facing forwardly away fromthe flue passage between walls 24 and 25 extends between' the cover andboiler wall 31. Baffie 106 isfreely seated on wall 31 so as to beremovable when the cover is taken off. 'A plate 108 secured to baffletop plate 106g projects over the top of the passage between walls 24 and25. The purpose of the cover and baiiie assembly is to extend over thetop of the secondary combustion chamber and to direct flow of the hotcombustion gases along the wall 23 as indicated by the arrows in Figure1.

Cover assembly 110 is secured to the top of the boiler unit as by studs110a.

Preferably the cover assembly and its association with the boiler is thesame as disclosed in said above men tioned Haugen patent, to whichattention is directed for any detail needed to understand the presentinvention.

A novel smoke hood and draft stabilizer assembly is mounted at the rearof the boiler. This assembly comprises in essence a head 111 which hasat opposite sides arcuate fianges 112 and 113 (Figure 6) secured as bybolts 114 `to the adjacent wall 17 of the boiler. Head 111 is forwardlyopen at 115 so as to provide an outlet which is continuous with thepassage between walls 24 and 25 for conducting the products ofcombustion from the secondary combustion chamber. Head 111 has arearwardly projecting bottom wall 116 that terminates at the juncture ofthe head with a vertical tubular passage defining member 117 thatextends down to the bottom of the cabinet. Tube 117 is closed at itslower end except for an opening wherein is fitted a short collar 118opening into cabinet space below the boiler. Air may enter collar 118and pass up the'tube 117 into head 111 to join the outgoing combustionproducts.

An automatic draft stabilizer assembly 119 is provided in the inner endof collar 118 and comprises a support plate 120 inserted into the openend of collar 118 and held there as by screw 121. A damper plate 122having pivots 123 at opposite sides journaled in support 120 serves tolimit entry of air into collar 118. Plate 122 has a recessed portionthrough which extends a threaded rod 124 on the lopposite ends of whichare mounted weights 125' and 126. Rod 124 is clamped to plate 122 as bynuts'127.

In operation, when the liue is cold, the weights are so located andbalanced that weight 125 exerts the strongest leverage to urge thedamper counterclockwise until a projection 128 encounters a fixed stop129 on the support. In this situation, damper 122 is almost closed andlittle or no air passes up tube 117. As the fiue temperature increases,the draft increases and the air fiow tends to rock plate 122 towardamore open position where it admits more air. Eventually a condition isreached where damper plate 122 assumes a fairly constant open position,which may be determined by preadjustment of the weights on rod 124. Ihave thus provided an arrangement'for maintaining a substantiallyconstant velocity draft in the heater.

At the upper end of tube 117 at the junction of the draft air and thecombustion products is mounted a deiector plate 131 having a fiangesecured to wall 116 and a deflector ledge 132 that extends upwardly andrearwardly at about 45 degrees whereby the air coming up through tube117 will be deflected outwardly thereby providing a controlled draftwhich will aid in movement of the products of combustion outward throughthe flue. The def tiector plate 131 insures against any tendency of theproducts of combustion to descend through tube 117. VAt its rear, head4111 is open to receive a short flue connecting tube 133 that projectsrearwardly through the cabinet wall (Figure 1). The above describeddraft stabilizer assembly 119 may be the same as that disclosed inUnited States Letters Patent No. 2,514,446, issued to ELA. Field on July11, 1950, to which reference is made for further de tail. The novelsmoke hood and draft stabilizer assembly of the invention may be used ina furnace as well as a boiler. f v

One decided advantage of this arrangement that particularly adapts itforthe kitchensV of small houses is that the entire draft ,assembly isVwithin the cabinet and the entire unit may be backed up fiush against awall in the kitchen with the projecting flue tube 133 thrust into aVfireproof ue in the kitchen wall. This is a novel and useful spacesaving feature which is made possible by the rarrangement abovedescribed in conjunction with the other parts of the apparatus.

A diaphragm actuated switch assembly 134 is mounted on the cabinet framenear the top of the boiler. A thermostat bulb 13S is mounted intheboiler water adjacent the suspended coil 13 and near the portion ofthe coil connected to the cold water inlet 93, so as to be quicklyresponsive to any change in thel boiler water induced by entry of coldwater into coil assembly 13. Thermostat 135, which may be of anysuitable conventional type, is connected by a fluid conduit 136,`fitting 137 and fluid conduit 133` to switch assembly 134 whichisincluded in a control circuit shown in Figure 1.

A second thermostat bulb 139 is mounted in the boiler water about aninch below the toprof the boiler as illustrated in Figure 2, so as tolie near the outlet of the coil assembly 13. It is connected by fluidconduit 141, fitting 142 and fluid` conduit 143 to switch assembly 134.

The circuit controlled by the switch assembly 134 comprises twoselectively operable circuits, one including the burner 16 and the otherincluding both the burner 16 and the pump motor 44. These two circuitsare in parallel and one or the other is selected by a suitablemanualswitch S for incorporation in the control circuit. When it is desired toenergize only the burner as will be described later,the rst of these twocircuits is included in the control circuit.` When it is desired toenergize both the burner and pump the other is included.`

The operation will now be further described. For summertime operation,or other periods when space heating in the house is not required, it hasbeen found that the domestic hot water supply may beadequatelymaintained by action of convection currents within the boilerwater space. Assume to start that the boiler water is hot and hassuitably heated the water within the suspended `coil assembly 13. Theabove-described manual l switch S is in open position to include theburner in the control circuit but not the pump motor.

When domestic hot water is drawn out of the coil assembly 13, theincoming cold water from pipe 93 `chills the coil and cools thesurrounding boiler water. When the temperature of the surrounding boilerwater drops below a predetermined amount, say 190 F., the thermostat 135acts to cause the burner 16 to be energized to start heating the boilerwater. Convection currents within the boiler water space will causehotter water at the bottom of the boiler to displace upwardly toward thecoil i3 and this circulation by convection within the boiler soonresults in even heating of all the boiler water and rapid raising of thetemperature of the water in the coil assembly 13. When heat exchangestability is established between the water in coil 13 and thesurrounding boiler water which has been raised aboveV the predeterminedsetting for the thermostat, the burner is deenergized. This feature ofrapidly following the change in temperature of the boiler water isextremely important in small capacity boilers such as that at 12.

The above provides an operational control insuring almost instantaneoushot water for the domestic tap. The thermostat at 139 provides a limitcontrol in that it prevents the hot water emerging from the coilassembly 13 from exceeding a safe limit. This control may be for exampleset to deenergize .the burner control circuit when the surrounding waterat the top of the boiler is at 220 F. or above. I have thus provided adual control for the domestic hot water which insures speedy response touse of the water and a safe limit control.

When the boiler water capacity is small it may be desirable as in thesummertime to speed upheating of the domestic` hot water by providingforced recirculation of the boiler water.. .This is done byelosing theabove described manualswiteh S to include both the burner and pump motor44 in the control circuit. The operation is then substantially as above,except for 'forced recirculation of the boiler water from the bottom ofthe boiler through conduits 57 and 54, pump 43iand conduit 49.`

8 Valve 48 may be closed at this time to avoid space heatingcirculation.

When it is desired both to heat domestic hot water and supply hot waterto space heating means such as radiators or panels, as in the wintertime, the above mentioned manual switch S is closed to include both theburner and the pump motor in the control circuit. The thermostats and139 act to control as above when domestic hot water is used. Valve 48 isopen so as to obtain the split flow described above in describing thepump connections. A conventional control thermostat (not shown)responsive to space heating demands independently of the thermostats 135and 139 is also provided. Thus, whenever the burner and pump motor arenow energized, water from the boiler water space is recirculatcd throughthe boiler and at the same time circulated through the radiator or panelsystem. The pump` must be large enough to handle both iiows. In aspecific embodiment of the invention, wherein hot water is drawn out ofthe bottom of the boiler and admixed with return water from the spaceheater panels so that the water at the pump outlet was 20 F. higher thanthe return water and 40 F. cooler than the boiler water drawn out of thebottom of the boiler, and the outlet of the pump was split betweenrecirculation of boiler water and circulation of the space heater water,a satisfactory pump flow rate was about 8.6 `gallons per minute, ofwhich 3.4 gallons per minute were recirculated boiler water and 5.2gallons per minute were space heater water. This ratio can be varied byadjustment of valves 53 and 48, and, in any installation, the flow rateis calculated according to the maximum expected loads in the boiler andpanel circuits. In the above, the maximum expected boiler output was80,000 B. t. u. of which 12,000 B. t. u. represented domestic hot waterrequirements and the maximum expected space heater load was 52,000 B. t.u. My invention requires a larger' pump than would be used in theconventional house heater boiler where the pump merely forces waterthrough the space heater circuit.

A thermostat bulb 144 is inserted into the head 111 above and forwardlyof deector ledge 132 which prevents thc upcoming cool air from directlyimpinging on the thermostat bulb. So protected by ledge 132, thermostat144 is directly and accurately .responsive to the tcmperature of theoutgoing flue gases. As illustrated in Figure l, the thermostat bulb 144is connected to a master relay device 145 which controls the entireelectrical circuit of the yheater and shuts off the burner should theflue temperature rise above a predetermined value.

Figure 7 illustrates an alternative domestic hot water heating coilassembly 146 wherein, instead of being made up of two separate coils,the coil assembly comprises a single continuous coil made up of eightvertical banks of convoluted tubing in series with its opposite endssecured to fixtures 147 and 148 that are clamped to plate 149 as by nuts151 and 152 threaded on the projecting fixture nipples above the plate.The coil assembly is stiliened by straps 153 and 154 which extendadjacent the respective from xtures down and around the bottom ofthestack of coils and are secured to the fixtures. The coil assembly ofFigure 7 is suspended in the boiler water in the same manner as that ofFigures l-6. The coil assembly 146 is arcuate to follow thecircumferential contour of the boiler walls and tit within the space 37without contacting the boiler walls, as in the earlier embodiment.

The heater above described is compact and etiicient and may be safelyplaced in a room having a combustible iioor. The body of the boiler isinsulated, as by a blanket of insulating fiber secured around wall 17,and very little heat is radiated into the kitchen. No separate hot waterstorage tank is required, as the boiler action is instantaneous andreliable.

The invention may be embodied in other specific forms without departingfrom the spirit or essential characteristics thereof. rIlhe presentembodiments are therefore to be considered in all respects asillustrative and not restrictive, the scope of the invention beingindicated by the appended claims rather than by the foregoingdescription, and all 4changes which come within the meaning and range ofequivalency of the claims are therefore intended to be embraced therein.

What is claimed and desired to be secured by United States LettersPatent is:

1. In heating apparatus, a boiler shell comprising a cylindrical outerwall and vertically spaced cylindrical inner walls surrounded by saidouter wall to deiine a boiler water -space therebetween, `at least theupper of `said inner walls being eccentric with respect to said outerwall to provide at one side a wide water space for receivi-ng a domestichot water coil, said inner walls detining combustion chambers, meansproviding a restricted throat passage between the combustion chambersdefined by said inner walls, a plurality of end walls completing closureof the water space between said inner and outer cylindrical walls, saidinner cylindrical walls being relatively thin sheet metal walls of highheat conductivity having smooth uninterrupted inner surfaces along whichproducts of combustion may flow without turbulence for enabling amaximum of rapid heat exchange between the products of combustion andthe water column in the boiler shell, said water space between theboiler walls being continuous about the combustion chambers except for alateral ilue outlet from the upper combustion chamber, and the upper ofsaid end walls having a circumferentially elongated opening above saidWide water space, a removable closure secured upon said opening, and acircumferentially elongated domestic hot water |heating coil assemblysupported on said closure so as to be suspended in said large area waterspace, the inlet and outlet connections to said coil assembly beingsecured to said closure member.

2, In heating apparatus, a boiler shell comprising an outer cylindricalwall member, an inner cylindrical wall member surrounded by the outermember, a wall member secured between the lower ends of said cylindricalwall members, `a second cylindrical inner wall member surrounded by theupper part of said outer member, an apertured top wall member securedbetween the upper ends of said outer member and said second innermember, at least said upper inner wall member being eccentric withrespect to said outer wall member so as to provide at one side anenlarged boiler water space below the aperture in said top wall and saidinner members being spaced vertically, a tubular throat defining memberbridging the space between said inner members, and spaced wall memberssecured between said throat member and the adjacent ends of said innermembers respectively, all of said wall members being sheet metal`elements secured together with water tight joints between them toprovide a permanent unit, a removable closure member for said top wallaperture, and a hot water heating coil assembly mounted on said closuremember suspended in said enlarged boiler water space.

3. Heating apparatus comprising a cabinet, a boiler in said cabinetsupported at a level to provide a space therebelow within the cabinet,said boiler comprising an internal combustion chamber closed at itsbottom above said space and having a tiue outlet through the upper partof a boiler side wall, a draft control assembly enclosed entirely withinsaid cabinet beside the boiler comprising means defining a passage openat its lower end into the cabinet space below said boiler and connectedat its upper end to said ilue outlet and draft regulating means withinsaid pass-age, and a flue connecting tube projecting from the upper endof said passage defining means through the cabinet.

4. In a hot water heater apparatus, a boiler unit, a

cabinet surrounding said boiler unit, means deli-ning a combustionchamber surrounded by said boiler unit and closed at its lower end by ahearth and burner assembly, a flue `conduit extending from the upper endof said combustion lchamber through said boiler unit, means enclosedentirely by said cabinet defining a draft control passage entending fromtop to ybottom of the cabinet having its lower end opening into thecabinet space below said hearth and bur-ner `assembly and having itsupper end connected at one side to said ilue conduit, a iiue outletconnection projecting from the other side of said draft control passagethrough the cabinet wall, draft regulation means in said passage belowsaid outlet connection, and means projecting into the upper end of saiddraft control passage defining means for deecting air rising throughsaid draft control passage outwardly toward said liue outlet connection.

5. In the heater apparatus defined in claim 4, said deecting meanscomprising an a-ngular ledge at the intersection of said passage andconduit.

6. In the heater apparatus defined in claim 4, -a burner controlthermostat responsive to temperature of outgoing products of combustionrfrom the boiler mounted in the upper end of said draft control passagedefining means so as to be shielded from 'draft air by said dellectingmeans.

7. In a hot water heating apparatus, a boiler having inner and outercontinuously curved smooth inner surface side walls bounding la watercolumn continuously surrounding ya combustion chamber, said side wallsat one side being spaced apart a greater distance than at other partsfor a predetermined arcuate distance to provide therebetween a wide coilreceiving space in at least the upper section of said water column, topand bottom walls on said boiler, the top Wall having a circumferentiallyelongated aperture above said coil receiving space, a plate remov-ablymounted over said aperture, and an arcuate coil assembly comprising aplurality of turns and shaped to follow the adjacent side wall contourssuspended wholly from said plate and disposed within said space out ofcontact with said side walls.

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